This invention relates to copper chemical-mechanical polishing processes using fixed abrasive polishing pads, and to copper layer chemical-mechanical polishing solutions specifically adapted for chemical-mechanical polishing with fixed abrasive pads.
In the manufacture of integrated circuits from semiconductor wafers and substrates, wafer polishing is a common technique utilized to remove material and/or achieve planarity. Such polishing can be conducted by purely chemical, purely mechanical or chemical-mechanical polishing means (CMP). With CMP, polishing and removal occurs by a combination of both chemical and mechanical-polishing action. CMP utilizes a combination of solid abrasives and chemicals to achieve the combination polishing action. One type of chemical-mechanical polishing utilizes a slurry comprising very hard, solid abrasive particles suspended in a chemical solution. The slurry is interposed between a pad and a wafer, with both typically being caused to rotate, and material removed from the wafer by both chemical and mechanical action. Another form of CMP provides abrasive material embedded within the surface of the polishing pad, and is commonly referred to as fixed abrasive CMP.
Unfortunately, conventional CMP slurries designed for non-fixed abrasive CMP create problems and do not always work satisfactorily in fixed abrasive CMP processes. This has been discovered to be particularly true in the CMP of layers where copper is present at greater than or equal to fifty atomic percent. Increasing interest is being focused on copper as a next generation material for interconnect lines in semiconductor circuitry fabrication. CMP of copper in processes of forming such lines will play a significant and valuable role in the fabrication of such circuitry. While CMP of copper has been reported using non-fixed abrasive pads and slurries, existing materials have proven less than satisfactory when using fixed abrasive pads. Accordingly, needs remain for improved chemical-mechanical processes using fixed abrasive pads and in the development of polishing solutions therefor.
The invention comprises copper chemical-mechanical polishing processes using fixed abrasive polishing pads, and copper layer chemical-mechanical polishing solutions specifically adapted for chemical-mechanical polishing with fixed abrasive pads. In the context of this document unless otherwise specifically literally narrowed, a xe2x80x9ccopper layerxe2x80x9d constitutes a layer having copper present at least at 50% molar. In one implementation, processes are described for pH""s of 7.0 or greater. In one implementation, processes are described for pH""s of 7.0 or less. Believed process mechanisms by which polishings occur in accordance with the invention are disclosed, but are not intended to be limiting unless expressly worded in the respective claim.
In one implementation, a copper layer chemical-mechanical polishing solution specifically adapted for chemical-mechanical polishing with a fixed abrasive pad comprises a copper oxidizing component present at from about 1% to 15% by volume, a copper corrosion inhibitor present at from about 0.01% to 2% by weight, and a pH of less than or equal to 7.0. In one implementation, a copper layer chemical-mechanical polishing solution specifically adapted for chemical-mechanical polishing with a fixed abrasive pad comprises a copper oxidizing component present at from about 0.1% to 15% by volume, a copper complexing agent present at from about 0.1% to 15% by volume, and a pH of greater than or equal to 7.0.